This article also appears in
Subscribe now »

An F-15 outer piston is anodized and sealed with new potassium permanganate sealer at Ogden Air Logistics Complex. AFRL researchers identified and tested this non-chromium sealer as a safer alternative to chromium-based products, and it is now fully incorporated into OO-ALC’s coating process. (U.S. Air Force)

Uncovering safer solutions for aircraft corrosion prevention

Working with aircraft maintainers at the Ogden Air Logistics Complex, researchers from the Air Force Research Laboratory's Environmental Technology (EnviroTech) Program and Coating Technology Integration Office have identified and tested a variety of non-chromium sealers to anodize aluminum aircraft landing gear components to reduce and prevent corrosion.

AFRL's EnviroTech Program executes development and demonstration of alternative environmentally preferred technologies. The EnviroTech mission is to scope and develop technologies to meet user requirements, progress solutions through Technology Readiness Levels, and highlight technology transition activities for U.S. Air Force enterprise use.

Non-chromium coatings and materials are increasingly important to the USAF because of the harmful nature of chromate-based products. Chromium is listed on the U.S. EPA's list of industrial toxic chemicals due to its toxicity to humans if inhaled or otherwise ingested. In 2009, a U.S. DoD directive restricted the use of chromium-based compounds on military vehicles and weapon systems.

To find a suitable alternative material, AFRL researchers identified non-chromate materials that would perform similarly to the traditionally used sodium dichromate sealers. They tested various types of sealers by coating test panels and landing gear components and anodizing the components using the same process as maintenance depots. They also performed additional tests that were specific to the needs of OO-ALC.

After testing four different products, AFRL researchers identified a permanganate-based sealer―now being marketed as SafeGard CC-5000 by Sanchem, Inc.―that met, and in some cases, exceeded, the necessary criteria. They then presented the data to OO-ALC, where it was approved for use on landing gear wheels, brakes, and struts. In September 2015, the sealer was transitioned to OO-ALC and fully incorporated into the coating process.

According to Dr. Elizabeth Berman, AFRL Senior Materials Research Engineering, "The transition and full implementation of this material is critical as it moves toward more environmentally and health-conscious maintenance solutions. This safer material provides the same protection as the old materials."

Continue reading »